The use of mice and other small animals in cardiovascular research is increasing due to the availability of transgenic models and due to size and cost constraints. Ultrasound equipment designed for human echocardiography is unsuitable for evaluating cardiovascular function in small animals due to small organ size (5 mm dia heart) and high heart rates (400 to 600 bpm). We propose to continue development of a PC based low cost high resolution noninvasive diagnostic ultrasound device optimized for research use in animals ranging in size from mice to rabbits and with measurement resolutions on the order of 1 ms in time, 0.2 mm in cardiac dimensions, and 1 cm/sec in blood flow velocity. The functional 20 MHz prototype developed in Phase I will be generalized for 5 MHz to 20 MHz pulsed Doppler and M-Mode operation, EKG output, and enhanced to operate either standalone or by accepting analog inputs from existing clinical and laboratory equipment. Real time spectrogram, mean and peak velocity outputs will be generated using digital signal processing. The circuitry will be packaged as plug-in modules in a PC with software for instrument control, data display, analysis, and storage. The device will be validated with test signals, static and dynamic phantoms, and in mice. PROPOSED COMMERCIAL APPLICATION: The proposed system will permit accurate noninvasive physiologic measurements in small animals and has applications in cardiovascular research, transgenic modelling, and pharmacological studies. It can be used standalone or to expand the utility and function of the considerable installed base of pulsed Doppler and data acquisition systems currently used with implantable sensors in animal research laboratories. It will permit serial studies, allow the use of better, smaller and less expensive animals and could have a significant impact on the quantity, quality, and cost of medical research.